1. Field of the Invention
The present invention relates to vinyl alcohol copolymers having a terminal amino group and having good reactivity.
The present invention further relates to resin compositions having good mixing dispersibility.
2. Description of the Prior Art
Known vinyl alcohol polymers having a terminal functional group are polyvinyl alcohol having a terminal hydroxyl group via sulfide bond and one having a terminal alkyl group via sulfide group (Japanese Patent Application Laid-open Nos. 105410/1982 and 187003/1984). However, polyvinyl alcohol having a terminal hydroxyl group or terminal alkyl group could not give resin compositions having good mixing dispersibility with thermoplastic resins. Polyvinyl alcohol having a terminal amino group via sulfide bond is also known (WO 91/15518). The polyvinyl alcohol having a terminal amino group, however, could not give, when kneaded with thermoplastic resins, resin compositions having good gas barrier properties. Block copolymer of polyacrylic acid and polyvinyl alcohol linked via sulfide bond is known (Japanese Patent Application Laid-open No. 189113/1984). This block copolymer, however, is poor in mixing dispersibility with thermoplastic resins and hence could not give, when kneaded with thermoplastic resins, resin compositions having good gas barrier properties. Also known is polyvinyl alcohol having side chains of 0.5 to 30 molt of hydrazide group. This polyvinyl alcohol however has low crystallinity, thereby tending to have low water resistance, and could not give, when kneaded with thermoplastic resins, resin compositions having good gas barrier properties.
Vinyl alcohol polymers alone exhibit insufficient flexibility and mechanical properties and, to improve this, blending with other thermoplastic resins such as polyolefins has been practiced. On the other hand, thermoplastic resins alone, such as a polyolefin alone, do not have sufficient gas barrier properties and, to improve, blending with vinyl alcohol polymer has been conducted. However, vinyl alcohol polymer has poor affinity with and dispersibility in thermoplastic resins such as polyolefin, so that shaped articles and films comprising a blend of the above have markedly decreased mechanical properties or transparency.
To solve the above problems, Japanese Patent Application Laid-open No. 202638/1988 discloses a process which comprises blending an ethylene-vinyl alcohol copolymer having a terminal alkyl group and a polyolefin, and Japanese Patent Application Laid-open No. 88837/1991 discloses a process comprising blending an ethylene-vinyl alcohol copolymer and an polyolefin having introduced epoxy group. These processes, however, produce only small improvement effect and it has been desired to further improve dispersibility, transparency and mechanical properties of these blends.